text:
What is the rationale for single engine military aircraft?
In aeronautics, redundancy is of primary concern. Having at least two engines is common for civilian aircraft. I expect the military to have at least the same level of redundancy. Moreover military aircrafts are prone to other failure modes such as bullet in the airframe over a territory in which they cannot easily land (e.g. mountains or desert in which pilots can be captured).
I will restrict this question to jet fighters but I think it can be extended to any military aircraft.
I expect modern fighters to have at least two jet engines for redundancy. This is the case for many of them (such as the F-22 Raptor, the Dassault Rafale, the Eurofighter Typhoon, the Su-27 family, the F/A-18 Hornet, and others).
Yet, some modern fighters have only one jet engine (for instance the F-16 Fighting Falcon, the Saab JAS 39 Gripen, the F-35 Lightning II, and the Dassault Mirage 2000). Thus I imagine there are good reasons to abandon engine redundancy, but I fail to see what reasons can outweigh such a feature, especially for military aircraft.
What are the reasons behind the design of a modern jet fighter with only one jet engine?

There simply aren't many engine options for the class of the airplane. Like, if at the time of F16 there were a good engine with half a thrust, then YF17 would have won the bid. Does F35 have a choice, with F404 derivatives maybe? Not really. Could Chengdu J10 be made with 2 RD33s? No without throwing away a lot of performance. Reality is, the twin engine heavy fighters are the top performers and consumes huge amount of resource to develop, so if you want to develop a lighter fighter afterwards, you have a better bet by reusing its engine (core).

The safety "redundancy" of jet fighters is covered by the ejection seat

@slebetman a fifth gen fighter is an expensive thing to lose because of a ‘simple’ engine out scenario.... therefore it’s more about the trade offs (reduced purchase costs, reduced maintenance etc) than “oh, redundancy is covered because we can save the pilot” ;)

Single-engine fighters are usually not employed in the ground attack role where fire from the ground is an issue, neither are they usually used offensively abroad, where "mountains or desert in which pilots can be captured" can be a problem. Their role is defending friendly airspace, and checking out unknown or unresponsive aircraft flying into your territory (which almost always turn out to be airliners with a comm problem)

@Moo I'm merely answering the question of where is the redundancy in single engine planes as directly asked by the OP - because redundancy is already covered by ejection seats we no longer need to care about it when weighing in on trade-offs. Trade-offs now can completely ignore redundancy and focus on performance, cost etc.

@slebetman evacuation of the aircraft has its limits (e.g. over rough sea far away from the nearest boat, or in the middle of an enemy territory where search & rescue operation can expose more highly trained crews and expensive hardware)

More engines isn't always a more reliable/safer system. More engines = more complexity = more points for a catastrophic failure to occur

@slebetman : those who use the ejection seat will likely never fly again due to permanent injuries. Ejection seats save lives (and therefore raise morale) but they won't provide really "redundancy", as in the pilot hopping into another plane and flying again the same day. (still, single-engine fighters are rarely used over enemy territory)

@vsz The Netherlands have used F16 as ground attack aircraft (it was their only jet fighter until very recently) and are used offensively abroad, even in mountainous areas (including in recent Middle East conflicts). It's dangerous, sure, but your comment seems to indicate it's simply not done. It is. Often enough.

@vsz That's just untrue.  The F-16 even had a close support variant that got cancelled in favour of retaining the A-10 wings instead.  There have been other close support variants of the F-16 at various times, and they've certainly been employed in close support roles by various air forces at various times (including by the US during Desert Storm).

"I fail to see what reasons can outweigh such a feature..." on the contrary, weight is the reason.

@ManuH: Please don't delete your comments. This makes reading the comment threads pretty disjointed.

@dakkaron i delete them when they are obselete (i.e. taken into account in previous answer edition)

@ManuH But then you have half-threads where you only see the other person's comments. And the way conclusions were reached are lost.

@Dakkaron Anything useful in the comments should be put into the question or the answer anyway. Comments are third-rate citizens.

Fighters don't carry passengers.
The figure of merit for combat aircraft isn't passenger-miles flown between accidents, it's objectives completed (like enemy targets destroyed) per billion dollars spent. Adding redundant engines only improves this figure if single engine failures are very common.
Today, military engines have gotten much closer to civilian ones in reliability than before, and their failures account for only a small proportion of total losses. Single engines are more efficient, cost-effective, and cheaper to maintain.
In combat, for a fighter-typical near-centerline engine layout, a single destroyed engine is likely to also damage the other engine. This can be avoided, as has been done in the Su-27, by spacing the engines far apart and placing an armor plate between them, but that's even more weight.
Finally, jet fighters have one more safety feature. If an engine fails on takeoff in an airliner, everyone on board needs the plane to either take off or successfully abort the takeoff. A fighter pilot has a third option, eject and hopefully survive. The cost of this is, of course, destroying the aircraft.
This comes down to comparing two costs: that of total engine failure and that of preventing this failure. With modern engines, failures are rare enough that the occasional hull loss due to them is much cheaper than maintaining a second engine in every fighter just in case. This is very different from the 1960s-1970s, when engines were prone to malfunction.
For the most part, twin engines in fighter aircraft are becoming a fallback for when a single engine of sufficient thrust and reliability is not available.
Getting such an engine is a concern of its own - designing an engine powerful enough for a modern top of the line fighter is difficult. Since nothing except a heavy fighter needs that much thrust with supersonic capability, that engine will then only power a single aircraft type (in contrast to smaller engines, which find a variety of uses). So only the largest projects like the JSF can afford a custom high-end engine.

There are meritorious duties for a combat aircraft besides just destroying enemy targets. Reconnaissance and power projection don't always have measurable results, especially in peace time, but are still things militaries think are worth spending money on. ;)

Military mentality is closer to: maximize targets that don't need to be destroyed because the enemy knows not to mess with you. The word for is capability.

Now I'm curious about how are costs counted. Fuel, weapons and aircraft purchase and spare parts is the easy part. Training of all crews and people involved in making the aircraft and airbase work is hard to split between each aircraft type (and even more if you have both single and multi engines fighters operating from a single airbase)

Ejecting during takeoff? Didn't think it was possible under x thousand feet?

@Cloud Depending on the ejector seat, x can be as low as zero.  See https://aviation.stackexchange.com/questions/1439/is-there-a-minimum-altitude-for-ejection-seats

Because single engine fighters are substantially cheaper to purchase and operate.  Exact figures are hard to obtain, but as an example, an F-15 squadron will spend about 25,000 USD per flight hour whereas an F-16 Squadron spends about 15,000 USD per flight hour.   Effectively, you can purchase and operate twice the fighter force with single engine fighters than with multi-engine fighters.   This becomes very attractive for land based air forces belonging to countries with small defense budgets to operate the maximum number of combat aircraft per unit of currency spent.
Another major advantage to single engine fighters is maximized performance in a minimal size and weight package.  Adding a second engine will produce more thrust but at the cost of greater weight and fuel consumption.  This in turn requires more fuel be carried with a heavier airframe, creating a vicious circle for the design of these airplanes.  Typically in fighter design you want a specific weight ratio $W_a = W_{af}/(W_{af} + W_f)$ as low as possible.  This translates into an airplane which is a nimble, high capacity gas can with as low an empty weight as possible for a given range profile.  This is extraordinary difficult to do with a multi engine airframe.
The major advantage to a multi engine fighter is the same advantage that any other multi engine airplane has: they can carry larger payloads with greater system redundancy.   The large airframes accommodate big powerful fire control radars for detecting and tracking targets at very great distances, etc.  Certain units, particularly the United States Navy, prefer multi engine airplanes for overwater operations for the redundancy of having an additional engine to get you back home.   So too is this a design feature of the A-10 attack jet which anticipates enduring battle damage and the additional engine offers a better chance of limping it home if it gets shot up.
While the redundancy of two engines may seem ideal for combat ops, keep in mind an engine failure combined with the compressor and boat tail drag from the dead engine results in an airplane which has lost 50% of its total available engine thrust and 80% of its combat effectiveness.  All you could do after an engine failure would be to limp the airplane home to a friendly base - provided the enemy is gracious enough to let you do so without jumping your six and blowing you out of the sky!

How about fuel efficiency?

Fuel efficiency isn't often the forefront of military concerns @bogl.

@GdD, you probably refer to cost. How about range?

Maybe there's an answer there @bogl.

I agree @bogl, range is a very big deal to the military, and fuel efficiency creates range.

In addition to the valid points noted above, it's worth pointing out that at the relatively low failure rates for aircraft engines (even for military aircraft), adding a second engine just about doubles the probability of an engine failure. Also, a failed engine creates drag, so while actual thrust goes down by 50%, drag is higher so the effective thrust is even lower than that.

What are the terms in that weight ratio equation? I don't think it's very useful to to include an equation if you aren't going to define the terms

Wa = Specific weight ratio, Waf = empty weight of airframe, Wf = weight of fuel aboard at maximum capacity.

The other answers address the question "Why 1 engine?" but this begs the question: "Why do some fighters have 2 engines?" as actually, 1 engine is the norm for fighter aircraft. Note the list of 2 engine aircraft in the OP:

F-22 Raptor, the Dassault Rafale, the Eurofighter Typhoon, the Su-27
  family, the F/A-18 Hornet

With the exception of the F/A-18 these are air superiority fighters designed to outmanoeuvre, outrun and intercept enemy aircraft. Performance is more important than cost effectiveness here, reliability is not a major concern. The F/A-18 is a different story with the twin engine design chosen by the US Navy to support a wider variety of missions and higher level of readiness. A second engine normally reduces reliability but this was factored into the design of the GE F404 engines which were built for maintainability and reliability rather than performance.
For each of these aircraft, cost is not the driving factor though an advantage of having the extra power available is that they perform well as multi-role jets reducing the need for buying multiple airframes and all of the additional costs that comes with that (such as support, training, facilities).
Single engine fighters are the norm and provide a good balance of cost/performance with twin engine fighters only used when performance is much more important than cost or if the alternative is a small number of multiple airframes. There are exceptions of course such as the F-35 but there the high cost comes from the technology rather than the hardware.

You may rephrase your last paragraph. Is the hardware not a piece of technology?

Most importantly, the EF-2000 or the Rafale are peace time aircraft. Designed for training in peacetime when the public will be highly critical of a high accident rate. Compare that with the attitude 70 years ago when a British Parliament inquiry in 1947 was answered along the line "a 10% loss rate per year in peace operations is perfectly normal". Things have definitely changed since then.

@Manu H: What he means is development cost (technology) vs production cost (hardware).

The result of being shot up changed a lot for fighter planes over the years. Modern fighter planes rarely get hit by bullets, but rather by missiles. A missile hit usually takes out the whole aircraft, so there are far less instances where having a second engine would help the aircraft to get back home.
With this negating a lot of the reliability benefit of having two engines, the cost of having two engines outweighs the benefit in many cases.
I haven't expounded on the last sentence (cost/benefits) because others have explained that very well already. As to the ratio of bullets vs. missiles, that varies a lot depending on the type of aircraft and mission. Hard numbers will be very hard to come by. An A-10 is a plane that mostly flies slow and low in it's anti-ground missions. This plane will probably receive a lot more bullets, hence the dual engine. An F-16, which was primarily designed as a supersonic air superiority fighter will receive a lot fewer bullets since it flies fast and high. The faster and higher a plane flies, the harder it is to hit with a bullet (or any other ballistic projectile) and the more guided missiles need to be used to bring it down.
I googled a bit and every instance but one of an F-16 that got shot down was by some kind of missile. The only one I found of an F-16 that was shot down by bullets (https://www.popularmechanics.com/military/aviation/a27078461/dutch-f-16-flew-into-its-own-gunfire/) was one that flew into it's own gunfire.
I am sure there are other instances of F-16 being brought down by gunfire, but from the sample I found, the overwhelming majority were missiles.

Also, a two engine design could actually worsen reliability here - twice as likely to have an engine problem, and in combat one engine down might mean you are effectively out of combat.

Two engines are better than one for safety, but one engile is cheaper to develop and maintain. And these days modern engines do give you more bang for your buck so you don't need as many. Plus you get more missiles/bombs/etc. per kilo with a single modern powerful engine.
US pilots initially hated the idea of the F16 because it was small and had one engine. Look at most fighters of the same era, big and twin engines. But the F16 has since proved to be a very capable fighter.
The primary concern is the mission, second the pilot and last the plane. As long as you can get in and bomb, shoot, blow up or generally give your enemy a bad day then its job done. Getting the pilot and/or plane back home is a lesser concern.
I don't really get the rationale about 5th Gen fighters. Because they simply aren't that good. I mean a 5th gen fighter is only good against and 4th (or less) gen fighter. You couldn't get into a fight (especially with a decent 4th gen fighter) because you could't afford to lose one, they are such an expensive asset. And they are no good in a turning fight against older type specific aircraft. They seem to be build to kill you enemy from a long way off without getting into a close-up turning fight. Surely drones would be a much better way to go?
It's well versed that most military pilots are interested in the next newest shiny thing rather that its capability as a true out and out fighter or anything else. I'm thinking that if ever an F35 (say) end's up in a serious conflict, pilots will find to their cost that its sadly lacking.

You are correct my answer was a bit big to go as a comment so I added it as an answer but I will add to it to answer the question

The first two paragraphs address the question; the remainder is off-topic editorial that doesn't belong here.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Is AMS (Schiphol) Polderbaan the runway furthest away?
I'm very interested to learn if there are (m)any (major) (commercial) airports that have runways further away from the terminal(s) than Schiphol's Polderbaan. Which airport is "in the lead" in this respect?

The northern end of the Polderbaan, the last runway to be constructed, is 7 km (4.3 mi) north of the control tower, causing taxi times of up to 20 minutes to the terminal.
[...]
Newest runway, opened 2003.
Located to reduce the noise impact on the surrounding population; aircraft have a lengthy 15-minute taxi to and from the Terminal.

Wikipedia

Not sure on the distances but KDEN is a candidate.

@casey Using Google Maps measurement tool, the northern threshold of the Polderbaan is about 6800m (4.25mi) from the tower; the farthest threshold from KDEN's tower is about 4900m (3.1mi).

I think it's important to emphasise that the there's no space at the end of the Poolderbaan to turn planes, so the maximum distance used on a regular basis will probably be from the first taxiway.

I've sadly experienced this half-an-hour taxi on about 10 easyJet flights from Liverpool to Amsterdam.

@Manfred Good point. And that distance is only 5400m (3.4mi).

One possible contender is Pyongyang airport. The far end of the new runway (01/19) is around 7 km away from the terminal (as the crow flies). With taxi distance, it is almost 8 km:

Source
While the taxi times at Amsterdam can be very long, it is a bit misleading to blame it on the runway being 7 km away. Runway 18R is not used for takeoff. Unlike Pyongyang, there is no parallel taxiway on that 'end' of the runway, and Schiphol ATC would never want to wait for an aircraft to backtrack. Hence, it would be more sensible to use the distance from the first taxiway for landing aircraft on 18R, located 5.5 km from the tower.

From the Google Maps measurement tool, the end of the northern runway is about 6900m (4.25mi) from the approximate centre of the terminal area, so I think we have a new leader!

Note that the long taxi times are often due to parallel operations on 18C/36C, in which case airplanes landing from 18R have to take a large detour as crossing 18C/36C is generally not allowed during parallel operations.

source: Stack Exchange

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


text:
Why does climb gradient at Changi be at minimum of 6 and 7 percent?
Changi airport, Singapore, runway 20C and 20R both point into the sea with no significant obstacle to clear. There is no residential area down there. Next land mass is about 15 km away (Batam, Indonesia) so I guess noise abatement is less of a concern. What could be the possible reason for specify climb gradient at 6 and 7 percent?

I don't have a source for this particular notam, but most likely a temporary obstacle such as a ship or a crane (or a ship with a crane) is near the departure end of the runway.

@Jimmy yeah i have seen notam about crane and ship before but not sure it direct plane to go up until 2500 ft.

I've had ships completely shut down a runway before.

Geographical location of Changi airport
Singapore is on the Straits of... Singapore. This straits is the southern continuation of the Straits of Malacca, both form an international maritime road between Indian Ocean and Pacific Ocean, on a par with Suez and Panama.

(Source)
To add to the bustle, the Changi Naval Base, opened in 2004, is a mere 2 km East of the runways:

(Source)
If that was not enough, there is a shipping channel at the North of the airport, with two terminals near the runways: A ferry terminal, and a cargo terminal.
View of the waters South of Changi airport:

(Source)
Obstructions and climb gradient
Very large ships, including military ones can be close to the runway ends. When this happens, and to take a long takeoff into account, a large climb gradient is in use.
AIP for Changi includes instruction for obstacle clearance calculation.
On the North the climb gradient is at least 3.3%, but is increased based on ships actual height when ships exceed a specified height, and depending on the runway e.g. for RWY 02C:

When there are no reports of vessel movement along the northern
  shipping channel, or where the reported vessel height is less than 70m
  (230 ft) AMSL, the aircraft minimum net climb gradient shall be at
  3.3%.
Where the reported vessel height is 70m (230 ft) AMSL or higher, ATC
  shall advise pilots of the vessel height. Pilots, on receipt of this
  information, shall apply the minimum net climb gradient in
  accordance with the following table.

For RWY 02L, the height threshold is as small as 35 m and the gradient for a 110 m ship will be 10.7%, i.e. the gradient is twice.
On the South, because the traffic is larger and permanent, the guidance is different:

All departures on Runway 20C/20R shall be on a minimum net climb
  gradient of 5% until reaching or passing 400 ft. Thereafter, the
  minimum net climb gradient shall be 3.3%.

So what happened for this NOTAM to be published, requiring a higher gradient of 6 and 7% for RWY 20C/20R? Note this is only 1 or 2% steeper than it is usually. Different possibilities, no certainty:

The South protected area border is temporarily closer to the coast.
There is a very tall ship in the vicinity.
There is an obstacle on the land.

The general formula used for MOC calculation, for North and South departures:

For the above calculations, operators shall use the following
  information:
a. The most penalizing obstacle is a tall vessel which is
  on the extended center line of the runway. (ATC shall advise pilots of
  the height of the tall vessel.)
b. The required MOC is 0.8% of the
  distance (d) from the departure end of runway (DER) to the obstacle,
  in accordance with Volume II of ICAO Doc 8168 -  Procedures for Air
  Navigation Services Operations (PANS-OPS)  where, in the case of
  Singapore Changi Airport, the DER is defined as the end of the
  clearway.
c. The distance (d) for departure Runways 02L/02C is
  measured from the DER to the shipping channel north of Changi. The
  distance (d) for departure Runways 20C/20R is measured from the DER to
  the boundary of the restricted waters south of Changi wherein tall
  vessels of height above 49m (161 ft) AMSL are not permitted. The
  distance (d) for the various departure runways is as follows

The procedure above can be used by crews to calculate an optimized climb gradient, in case the default 5% is not retained. This procedure is used to provide pre-calculated MOC for North departures.
Now I want to see the actual departure from RWY 02C! Fly me!

I don't have it at hand but Singapore AIP seems to include 6 and 7 degree climb gradient for almost a year already. Will add more when I have better connection. Ps i look from SIN CAAS website for historical AIP.


text:
What is this equipment under the nose of this aircraft?
From the news of the Singapore Airline A330 nose gear collapse at Changi, I noticed some equipment under the nose part of the aircraft, which  somewhat damaged the radome when the nose gear collapsed.
It looks like some kind of ladder. What is it and what is it used for?
Note: it is during routine airline operation.

Hope you don't mind, I added a still from a news video

Here, avherald link. This is more reliable for aviation incident reports than mainstream media, because the information is more carefully verified. In this particular case it does not have more information, except a bit in comments, though.

As per the report published in the website:

In response to queries, SIA said the nose gear of the aircraft retracted while the aircraft was at Gate A17 undergoing a landing gear system check at around 8am on Sunday morning. At the time of the incident, there were no passengers or crew on board, but an engineer was on the aircraft.

Aircraft was undergoing on a landing gear system check, so engineer is using the ladder to reach out the complete system.
Yes, it is ladder. Also you can see some other picture which shows the door tore apart due to air bridge because of landing gear crashing.


text:
How are runway conditions measured?
Which method is used to measure the runway conditions?
Is it impossible to land on a contaminated runway?

Are you asking specifically about runway contamination? If so, you might want to ask how "contamination" is defined and measured. Or do you mean something more general like how runway surface friction is measured?

Measurement
Runway conditions are measured using a friction standard: ICAO Circular 329, Runway Surface Condition Assessment, Measurement and Reporting.
Local regulation applies too, e.g. for UK: RA 3272 – Continuous Friction Measuring Equipment.

Adequate runway friction characteristics are needed for three distinct
  purposes:

deceleration of the aeroplane after landing or a rejected take-off;
maintaining directional control during the ground roll on take-off
  or landing, in particular in the presence of cross-wind, asymmetric
  engine power or technical malfunctions;
wheel spin-up at touchdown.

(Source -- Source also used for most of the technical details in this post)

Continuous Friction Measuring Device / Equipment (CFMD / CFME)

(Source: Team Eagle)

(Source)

Decelerometer, Brakemeter, Dynometer... for snow and ice.

(Source: Sherwin Industries)
Minimum Friction Level (MFL) μ is specified by local air authority. A value less than 0.34 is seen by ICAO as slippery.
Friction is measured for each third of the runway, in a direction parallel to the runway centerline.

(Source)
Reporting
Runway friction coefficient should be measured at least daily and reported via NOTAM if needed. NOTAM codes for friction measurement equipment:

BOW Bowmonk Decelerometer
BRD Brakemeter-Dynometer
ERD Electronic Recording Decelerometer
GRT Griptester
MUM Mark 4 Mu Meter
RFT Runway friction tester
SFH Surface friction tester (high pressure tire)
SFL Surface friction tester (low pressure tire)
SKH Skiddometer (high pressure tire)
SKL Skiddometer (low pressure tire)
TAP Tapley Decelerometer

A contamination terminology is used for a qualitative description of the runway condition. It can be used in complement of the friction coefficient value, or alone when a measure is not possible.
Sample for water on the runway:

DAMP: the surface shows a change of colour due to moisture.
WET: the surface is soaked but there is no standing water.
WATER PATCHES: significant patches of standing water are visible.
FLOODED: extensive standing water is visible.

Other terms exist for snow, ice, etc.

A runway or portion thereof shall be determined as being slippery when
  wet when the measurements with a CFME + self wetting tyre shows that
  the runway surface friction characteristics are below the minimum
  friction level specified by the State.

NOTAM sample:
NOTAN A1713/11 Chennai Airport ( VOMM ),  India
A1713/11 1111220910/1112231200 EST RWY
RWY 07/25 LIABLE TO BE SLIPPERY WHEN WET.
THE VALUE OF COEFFICIENT OF FRICTION IS BLW
THE NOTIFIED VALUE OF 0.34 FOR RWY 07/25
IN SECTION AS BLW :-
RWY07 BTN 400M AND 650M
RWY25 BTN 300M AND 500M

As commented by @RonBeyer (thanks!), pilots can also provide their own observations about braking conditions to ATC using PIREPS. PIREPS are voluntary reports by pilots to share information with ATC and other pilots. They are valued because they are current and they may be the only information available at small airfields.
ATC and recorded bulletins provide runway conditions to pilots, in addition of NOTAM.
Impact on roll distance
Weather has many impact on operations, but runway contamination particularly impacts landings, due to the loss of braking capacity. Take-off are also impacted, mostly at the beginning of the take-off roll, when the control surfaces are not active. Runway condition is also important to take into account if a take-off has to be rejected.
A degraded runway condition decreases the longitudinal stability and increases the roll distance:

Note: As mentioned by @Yos233, autobrake LOW and MEDIUM have been inverted
(Source)
Thrust reversers are particularly useful when the runway is not dry:

Note: Autobrake LOW and MEDIUM still inverted
(Source)
Pilots will use similar tables to determine if they can land or take-off. A flight management computer can also be fed with the runway condition for roll distance determination..
Aircraft are tested for their ability to cope with different runway conditions:

A340 test on artificially flooded runway (source)
Note that it is possible to land and take-off quite easily on compacted snow -- and, albeit more difficult, on ice -- taking into account the coefficient of friction:

Alton Bay runway (source)

More

Description of Various Friction-Measuring Equipment
Used in Winter Operations (appendix A)

Only thing I say you are missing are PIREPS (pilot reports). Usually when flying around at the untowered fields, I'll provide the nearest control facility information about runway conditions and braking action since a lot of times the information they have is old and unreliable.

@RonBeyer: Thanks, indeed PIREPS are important data, I have added your input, but feel free to edit my answer directly as you like.

Off topic, but why does the autobrake medium result in a longer landing roll than the autobrake low? Shouldn't the opposite be true?

@Yos233: Nice shot! You are right. The caption has been inverted, the reason is probably that they had to replace a solid line by a dashed line when they converted from colors from this document. However the latter has another anomaly that you'll likely find :-)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Can a GPS waypoint be used when filing a VFR flight plan?
This probably equally applies to IFR flight plans, but the general question is can arbitrary (unrelated to an airway or named fix) GPS coordinates be used in the route on a flight plan?

Can you clarify whether you mean lat/ lon coordinates provided by the pilot, or official pre-defined waypoints published by the FAA (if in the US)? See comments below other answers for more.

@quietflyer Question updated. Whether or not they relate to a defined waypoint probably wouldn't matter, I'm just asking if they will accept lat/long coordinates in the route.

The AIM specifies how flight plans should be filled out, block 8 contains the route of flight:

Block 8. Define the route of flight by using NAVAID identifier codes and airways

It is possible to do this if you can fly at or above FL390, since you need to get through class A airspace to get to FL390 you can not get to FL390 on a VFR flight plan alone.

Pilots of aircraft equipped with latitude/ longitude coordinate
  navigation capability, independent of VOR/TACAN references, may file
  for random RNAV routes at and above FL 390 within the conterminous
  U.S. using the following procedures.
...
Define the route of flight after the departure fix, including each
  intermediate fix (turnpoint) and the arrival fix for the destination
  airport in terms of latitude/longitude coordinates plotted to the
  nearest minute

I don't think there is anything in what you quoted that precludes a pilot from filing VFR below FL 390 using GPS waypoints.

@MichaelHall "may file for random RNAV routes at and above FL 390"

@MichaelHall the way I read the question was if pilots can file with arbitrary lat/long points "can GPS coordinates be used", defined waypoints are aloud.

The AIM only references RNAV under the IFR filing section, for VFR it does not discuss it. But if we assume that anything it's ok to do on an IFR flight plan route is also ok on a VFR route, then it does say this about RNAV: "(e) Define the random route by waypoints. File route description waypoints by using degree-distance fixes based on navigational aids which are appropriate for the altitude stratum."

@hemp since its above FL390 you would not be able to get there any other way than an IFR flight plan as you would need to go through Class A airspace.

@Dave, I'm not sure if you are agreeing or disagreeing with me...  "May", or being allowed to do something in one scenario doesn't restrict that same thing from another scenario.  Is there a specific restriction against using GPS waypoints under VFR?  If so, quote that.  If not, by default it is permitted.

@MichaelHall I guess what Im saying is that its a logic trap, the IFR permission is only for flights above FL390 which you can only get to on an IFR flight plan (Through class A). The VFR flight plan regulations for filling out Block 8 clearly state that only NAVAID id codes and airways are to be used (above quote). The latter part only applies to IFR as its written even though it does not explicitly state it.

And what I am saying is that the word "only" does not appear in your quote.  Consider the following two statements:  "The AIM only mentions filing VFR using airways and NAVAIDS."  And:  "The AIM states that when filing VFR you can only use airways and NAVAIDS."  Similar, yet very different meanings.  And only the first one is true.

@Dave, the section of AIM I referenced is not with regard to FL390, it is a general purpose statement about RNAV and states that you would use fix/radial/distance notation (not lat/long coordinates.) The section for FL390 and above is the only place I've seen where lat/long coordinates are discussed as being acceptable.

Yes, nothing prevents you from doing so, and it is quite common.
Flying VFR does not require you to actually navigate by means of visual reference, it just requires you to remain VMC in accordance with the airspace class you are in.

What is the format for GPS coordinates that Leidos Flight Services will accept?

@hemp Don't know what Leidos Flight Service is, but the format to use in flightplans is standard WGS84 DMS coordinates, such as 382338N 0763251W

Leidos Flight Service, formerly known as Lockheed Martin Flight Service, is the official FAA flight plan filing service (1800WXBrief). Is there a reference somewhere stating that WGS84 is the correct format to use? The AIM says "Record latitude/longitude coordinates by four figures describing latitude in degrees and minutes followed by a solidus and five figures describing longitude in degrees and minutes." under 5-1-8.

@hemp I really don't know about rules for just one specific country. You should have specified in your question if you were asking specifically about the USA. Regardless, WGS84 is the standard format used for aviation worldwide.

Do you have a reference that specifies WGS84 as the standard format used for aviation worldwide?

@hemp ... any aviation document you will ever find that contains geographical coordinates

Considering I just directed you to one that uses a different format, that seems like a bogus answer.

@hemp DMS is the format. WGS84 is the Geodetic System.


text:
How is propeller thrust vector accurately expressed for airplanes and multirotors?
For propellers, as the airspeed increases thrust decreases. Is the airspeed component taken as a vector quantity perpendicular to the propeller? If that's true, then it's quite easy to visualize in the case of airplanes.
However, for quadcopters can the forward component of the thrust vector of a quadcopter type rotor be expressed as:
$$
V_q\cdot{sin}\theta_t
$$
Where:

$V_q$ is the forward airspeed of the quadcopter, and
$\theta_t$ is the angle of rotor tilt

Is this an accurate expression of the thrust vector?

Welcome to Aviation.SE could you please clarify what you are asking for?

Note for a tilting helicopter (and I guess a quad too), tilting forward produces forward motion, and this generally increases lift too. So it's a lot more complex than just taking the cosine of the tilt angle.  Also, you might want to edit and rephrase your question as it's not 100% clear what you mean.

I think this question should stay open, but the OP really needs to clean up the formatting so it's easier to follow...please?

I have attempted to clarify the formatting and wording. If my edit is too presumptive it should be rolled back.

The term
$$V_q\cdot{sin}\theta_t$$
is a speed, not a force, so it cannot be an accurate expression of the thrust vector.
Propellers accelerate the air flowing through the propeller disc in the direction of the propeller axis (or perpendicular to the propeller disc), so the force is only parallel to the propeller axis when the airspeed is aligned with the propeller axis. If the airspeed is at an angle to the propeller axis, the thrust vector is tilted towards the airspeed vector. The magnitude of this tilt depends on the speed increase of the propeller stream relative to airspeed.


text:
What percentage of airliner flights globally are freight flights?
So we have N airliner flights in the world each day. What percentage of them are "purely" cargo flights versus passenger flights (that may carry cargo as well)? We can exclude Combi aircraft and other intermediate cases for the sake of simplicity. Thank you.

There is no straight forward answer. Apart from it being pretty difficult to find accurate and global data, you must also consider how to count flights that carry both cargo and passengers. Some normal passenger flights will carry some amount of cargo as well, and there are planes such as the 747 Combi which has passengers in the front and cargo in the back.

@J.Hougaard they should have called it the "747 mullet"

The US DoT statistics might be a starting point. They say that in April 2016 there were 755,000 passenger flights and 55,000 cargo ones by US air carriers, but I don't know what those numbers really mean, e.g. how they define "cargo". As @J.Hougaard said, many (most?) passenger flights carry freight anyway.

Thanks for your answers! Yeah, I was interested in passenger (maybe with cargo payloads) vs "purely" cargo. We can exclude Combi and other peculiarities. Thanks for the US statistics! A good starting point indeed.

Do you include small bush planes or only jets ?

@Federico, thank you!

@Antzi, only airliners.

Related: http://aviation.stackexchange.com/questions/8668/how-many-active-large-commercial-airplanes-are-there/8690#8690

The National Air Traffic Controllers Administration states that:

"On any given day, more than 87,000 flights are in the skies in the United States. Only one-third are commercial carriers, like American, United or Southwest. On an average day, air traffic controllers handle 28,537 commercial flights (major and regional airlines), 27,178 general aviation flights (private planes), 24,548 air taxi flights (planes for hire), 5,260 military flights and 2,148 air cargo flights (Federal Express, UPS, etc.). At any given moment, roughly 5,000 planes are in the skies above the United States. In one year, controllers handle an average of 64 million takeoffs and landings."

Therefore, if there are 28,537 commercial flights and 2,148 cargo flights;

28,537 + 2148 = 30685
(100 / 30685) * 2148 = 7.00016294606%

Thus there's for all of the airline flights taking off daily, 7% of them are cargo, and the rest are commercial.

Can you provide a link to where you got that quote from, please? Looks like interesting reading.

Sadly I can't find the quote on the NATCA website, but it could be found on many other websites: link, link2

You came up with some numbers, but they don't really address the question that was asked.  The OP asked about the percentage of total ait flights internationally that are cargo flights, and you gave an answer for the USA, with a percentage that doesn't relate to the total number of flights, even in the USA.


text:
What is this aircraft, and what country makes it?

What is this aircraft and what country produces it?
Source: Google Images

Please credit the source of your image.

"Google Images" is almost certainly not the source.

I saw it on Google Images, saved the image, then put it on the question.

@anonymous May I ask why you accepted the other answer and not mine? Just curious.

This is a Raytheon Sentinel R1, which is produced by Raytheon (US) and Bombardier (Canada). The aircraft in your picture is operated by the Royal Air Force.

(Image Source: WikiPedia - Author: Alan Radecki)

This is a Raytheon Sentinel, built primarily for the United Kingdoms Royal Air Force.
In fact, the same aircraft is pictured on the Wikipedia page:
https://en.wikipedia.org/wiki/Raytheon_Sentinel

@Andrew Notice the number on the engine... same aircraft.


text:
How does the battery master switch activate the battery contactor in Cessna 152?
I have trouble understanding how the battery master switch activates the battery contactor in this schematic from the Cessna 152 manual. This is the model from 1979 or later with an Alternator Control Unit.

Image source: Flight Literacy
I believe that the battery contactor is a relay that connects the top and right contacts (as in the image), when the left contact is powered.
Initially, all switches are off, the alternator is not turning, and there is no oil pressure:

The left contact of the battery contactor is connected to ground via the battery master switch in off position.
The battery contactor is not powered. It disconnects the battery from the connection through the Ammeter to the primary bus.
The battery voltage is distributed only to the clock and the oil pressure switch.
The two diodes close to the battery contactor are in reverse bias and therefore not conducting.

When I change the battery master switch to the on position, I expect that the battery contactor is closing the contact, and connects the battery via the Ammeter to the primary bus.

That requires power on the left contact of the battery contactor.
The battery master switch connects this contact (via "Alternator field circuit" breaker and "Pull off ALT" breaker) to the primary bus.
The primary bus is not powered yet.
In the way I read this schematic, the battery contactor cannot be activated. Nothing happens.

What am I missing?

See picture below of the C152 electrical system.

The battery contactor is a solenoid controlled relay.  The battery is connected directly to the input terminal of the contactor and this terminal and the BATT switch terminal on the contactor remain electrically hot as long as the battery has charge.  When the BATT MASTER switch is energized, this provides a path from the hot input terminal of the contactor to ground, causing current to flow from the battery, through the contactor solenoid and to ground (yellow path).

The energized solenoid makes contact between the input terminal and the and the main bus bar, energizing the airplane’s electrical system (blue path).

Current from the battery also passes through the ammeter enroute to the bus bar, indicating the rate of current either from battery discharge or battery charging provided by the alternator.
If the ALT switch is not energized, The overvoltage sensor is grounded, thereby preventing the regulator from supplying power to the alternator field coil and the alternator from producing electricity to be fed into the bus (purple path).

This causes the OVER VOLTAGE light to illuminate, indicating that the alternator is either not producing power to the aircraft electrical system, or the electrical system is operating at an abnormal voltage.
Current to the main bus bar from the alternator may also be interrupted by means of the ALT circuit breaker.
If the ALT switch is energized, the overvoltage sensor is not grounded, battery power is supplied to the regulator, which in turn energizes the alternator field coil (orange path), thereby allowing the alternator to generate electricity at a voltage greater than the battery (green path) when the engine is driving it.

The diode fitted between the two contacts on the battery contactor allows the alternator to charge the battery during engine operation.
Alternatively both the aircraft’s electrical bus and battery charging can be operated by connecting an external power plug into the A/C’s external power socket (red path).

I think two of my premises were wrong.

The battery contactor is activated by connecting the left contact to ground (instead of 24 V as I thought). It works different from the starter contactor (which has a permanent ground connection).
The battery master switch toggles between ground [on] and floating [off] (instead of primary bus [on] and ground [off] as I thought).

Like this, the plane will be able to start!

The left connection on the contactor is brought to ground on the right, BAT, side of the master switch.  That allows current to flow between the center contactor terminal and the left contactor terminal.

The battery contactor is a solenoid.  Closing the BAT switch to ground activates the solenoid, which then physically closes the circuits providing power to the bus boards and starter switch from the battery.
The starter switch connects to yet another solenoid, which sends power to the starter motor.  In exactly the same way as the battery contacter, the starter solenoid reopens when the key moves out of the "start" position, stopping the current flow required to keep its "switch" closed for the starter motor once the engine is running on its own.


text:
Why aren't there more stringent checks for switching off electronic devices during takeoff-landing?
I understand from discussions such as these, that it is crucial that to avoid electronic interference with flight instruments, all electronic devices should be shut off during takeoff and landing. And yet, in my experience, there are always rebels getting away with brazenly keeping their instruments on.
My question is, given the critical nature of possible interference (tiny probability but catastrophic consequences), why aren't airlines looking at more stringent measures than a routine announcement/request by the pilot? For example manual checks, frisking?

Interestingly @fooot link refers further to Are personal electronics a risk to commercial aviation?. Note that cell phones were not forbidden by FAA (in the US) but by FCC, and I believe it's to protect the ground network cells, not the aircraft. It is not possible to stay connected to a cell, the cell phone will keep contacting cells one after the other without disconnecting correctly, due to the cell size (some km) and the aircraft speed.

There are some problems with this as electronic equipment are not banned in aircraft per se, but only during some (critical) phases of flight.

First, how to determine if someone is operating electronic instruments. It'll be difficult, considering that everyone is seated. The only way is to put a lot of cameras (who's going to monitor them?) or by asking everyone to check their fellow passengers, hardly a good option.
Even if someone operating an electronic equipment is detected, what to do? During takeoff and landing, seat belts are mandatory and the only option (except announcing the seat number over PA) is to ask the person in nearby seat to snatch the offending equipment; again not a good solution.

As most of the electronic equipment (like camera or music players) emit little radiation and no air crash has been attributed to use of electronic devices, I doubt airlines will do something to physically to prevent passengers from using electronics.

There is a huge difference between cameras and music players and devices which intentionally radiate RF.  They cannot be compared.  A friend of mine is an avonics trainer for my regional airline and he confirms that mobile phones do interfere, mostly with the audio systems.  Pilots have reported "missing the odd clearance" which is not a big deal.  However, who wants to take the risk even with this?  "Fast plane 297, immediate avoiding action,  turn".  Responded with "station calling, say again, left or righ.....bang".


text:
Why is this G-AIRMET's valid time earlier than its issued time?

For this G-AIRMET map, why is the valid time earlier than the time it was issued?

These are created manually by a weather forecaster using data from a specific point in time, and most likely there was some kind of delay in issuing the chart so they came out late.

Sounds more like an answer than a comment, @Lnafziger. Make it so, Number One!  :)

Might be a duplicate. This answer seems to (maybe indirectly) address this: http://aviation.stackexchange.com/a/22893/11953  "From this table you can see that the 6-hour forecasts are usable from the time they are issued until 3 hours after the valid time. The 12 hour forecasts are usable from -3 to +6 hours of the valid time and 24 hour forecasts are usable from -6 to +6 hours of the valid time."

But then again it might be talking about something completely different - I'm no expert :)

@freeman That's what I think, and if I was more confident I would, lol.


text:
Thought experiment: can an aircraft that is dropped from the sky get into gliding?
Here's a totally hypothetical question that came up in a discussion with friends:
If a commercial aircraft (say, an Airbus A320) was "dropped" from a typical cruising altitude (say, 35,000ft) with a current ground speed of zero and all engines off, would it be possible to get it into gliding by putting the nose down, and how far could it go?
The much more practical question "how far can an aircraft glide" is already answered (e.g.,
How far can airplanes glide?), but it would be great if somebody could participate in this thought experiment with no engines and no initial speed.

With no power and no airspeed, you could not get the nose down.  I don't think you will find an accurate answer since it's never been tested or modelled but my guess is that it would just continue to fall in a flat attitude until boom.

You may search online under "balloon launched glider" as this the idea. This is done regularly, either RC aircraft, or actual aircraft. Note that a null ground speed does introduce the possibility of some relative airspeed, and even a large one, due to wind. When the glider is released with a null airspeed, gravity will accelerate it, initially at a 90° AoA, thus in a stalled condition.

@Simon: The cg of the aircraft is almost always ahead of the center of its projected area, so it will pitch down quickly. If it is naturally stable, it will then recover to a glide corresponding to its trim setting (given is has sufficient altitude).

In addition to what Peter Kaampf said about cg i would think that if dropping in a flat attitude the horizontal stabilizer would create significantly more drag at the rear, pitching the nose down.


text:
How many commercial jetliners are equipped with ADS–B?
The Wikipedia page for Automatic Dependent Surveillance – Broadcast (ADS–B) explains that the aircraft surveillance technology is being phased-in around the world currently, with some due dates in 2017 and 2020 and so on. I see organizations like FlightAware.com are deploying their own ADS-B receivers and are crowd-sourcing data from homemade receivers as well. That leads me to wonder…
How many commercial airliners are currently equipped?
Any reports or estimates by airline or by country/region?
Also: Are private jets being equipped? Are small aircraft being equipped?

The majority of commercial airliners are currently equipped. I don't have the latest statistics, but for Europe over 80% of the airliners were equipped with 1090 Extended Squitter ADS-B two years ago. The percentage in the USA was similar but a bit lower.
That doesn't mean that all those aircraft are compliant with the European rules that mandate ADS-B for these aircraft from 2020 onwards. To be compliant, the aircraft need to have ADS-B version 2 (EUROCAE ED-102A / RTCA DO-260B compliant transmitters) and the installation in the aircraft has to meet certain criteria. At this moment (May 2016) I estimate the percentage of rule compliant airliners to be less than 20%. I haven't run statistics on my own dataset for a while, I may update this figure over the summer.
In Europe, all aircraft heavier than 5700 kg maximum take-off mass or a maximum cruise speed exceeding 250 knots true airspeed are subject to the ADS-B rule.
Therefore private jets and some small propeller aircraft will need to equip with ADS-B as well. In addition many people voluntary equip their aircraft with ADS-B; it is not uncommon to see ADS-B equipped gliders in Europe.
The situation in the US is a little different. The FAA mandate requires aircraft flying in certain airspaces to equip with ADS-B. In my view this makes more sense since it will prevent a mix of equipped and non-equipped flights in one airspace.
In the USA, two types of ADS-B are allowed. The 1090 ES is required above 18 000 ft, below that altitude Universal Access Transceiver is also allowed. This causes all kinds of interoperability problems that can only be fixed at high cost.
The FAA mandates aircraft in the 48 contiguous states (and D.C.) that operate in class A, B, or C airspace or class E airspace above 10 000ft (class E airspace below 2500 AGL excluded) to be ADS-B OUT equipped by January 1st, 2020. The mandate itself can be found here and the associated Advisory Circular (AC90-114) can be found here.
This means many more aircraft are subject to the rule. I have no recent information on what the implementation status is.


text:
Can airliners be considered as GA?
In a Swiss001 video, he said that the Twin Otter was a general aviation (GA) plane. But then in another video, he said that the Twin Otter was an airliner. Obviously, he's not a credible source, but it does make me wonder: Can airliners be GA aircraft planes at the same time?
(I mean, some airlines do operate King Airs to remote destinations)

Who said this, in which videos? Why is he not a credible source?

@CatchAsCatchCan: I don't remember the videos, and obviously he is not a credible source because he is a youtube that creates gaming videos, and not an educational channel, and even some educational channels might be uncredible

Why is it obvious that 'he is not a credible source'? I have no idea who you're talking about. Either explain properly where you got your references so that we can follow the train of thought, or consider whether you can reword the question to omit the noise.

See also At what point does an aircraft become an airliner?

It depends on the context. For example, under CASA regulations they set the boundary between the two at a certain gross weight and this means there are a whole new set of rules for GA. At the moment our industry is undergoing change trying to better define the rules. Have a look at the differences between CAR30 and a part 145 if you are interested (but it is dry reading). EASA and FAA will define it different as well although I am not as familiar with those as I do not teach them. So you would need to go look at the regulation under the jurisdiction that the aircraft is operating.

I think in the US you would consider anyone flying under Part 91 to be GA and airlines, charter, and package to be commercial. So corporate jets would be GA but a Cessna 206 flying packages would not.

@CatchAsCatchCan : It doesn't really matter anyway since it is not the main part of the question, it was just something to start off with.

@CatchAsCatchCan Presumably, he isn't a credible source because he has no relevant credentials that might give him credibility. In other words, why would a gaming channel YouTuber be regarded as an authority on terminology relating to a subject they have likely not studied in any formal capacity? I think that statement doesn't merit any further justification, nor would such justification actually be useful to the question.

GA refers to why you fly your plane, not what kind of plane it is. For example, John Travolta has (had?) his own personal Boeing 707, which is the first generation of jet airliner from Boeing. When he flew it, it was not under scheduled service, so it would be classified as a "general aviation" flight.

Yes, this.  And we have a local airline that flies Cessna 206s.

And who is after big things buy A380. I am not sure if it is really not for charter flights or something the like but as it is for "undisclosed customer" who imagine "cannot wait" (and airlines can?), I think this is likely. Then that huge aircraft would join the fleet of general aviation.

It's not all that uncommon to have 737s &c, and even the occasional 747 owned & used by private individuals - that is, not corporate or charter.  So they'd arguably be "General Aviation", no?

Military flights are also classed as "general aviation", so, when SAM 29000 is carrying the president around, that's technically a general-aviation flight.  :-P

@Sean, where did you hear this?

@Sean Military flights are not considered as GA because, among other things, they don”t have to follow any of the FARS—including Part 91. The president always flies on military aircraft, so no, he’s not flying GA.

@JScarry but there is executive one for a reason, right? I read somewhere one of the president flew on normal scheduled airliner and had executive one callsign.

@vasin1987 True. There is an Executive One callsign. If Trump flew on his own plane, it would be Executive One, but I don’t thnk he ever did. According to Wikipedia, President Nixon flew on a scheduled airliner in 1973, but I don’t think any other Presidents have.

@vasin1987: In this day and age, I doubt that will ever happen again. The Secret Service is very strict about how the President is transported. Generally, they will use The Beast, one of the HMX-1's VH-3D or VH-60N helicopters, or one of the VC-25As. If necessary, they bring all of those with them. Moving the President actually requires moving a small village, so there wouldn't be much of a point to using a commercial flight, as e.g. The Beast cannot be transported in a normal cargo plane. They only use fuel from US military bases, if there are none, they even bring their own fuel!

The opposite of what you ask about did actually happen in this millennium: When George W. Bush made a surprise Thanksgiving visit to the troops in Iraq, he flew on one of the VC-25As, but they pretended to be an executive jet. It was also one of the rare occasions where the President was not using The Beast to travel by car. Instead, he travelled to the airport in an unmarked car and without a motorcade. He also famously flew to an aircraft carrier using a jet (which then had the callsign Navy One).

When it looked like an important vote was coming to a tie and the Vice President's tie breaker vote would be needed, Vice President Al Gore used a US Airways Shuttle flight to get to Washington because there was no other way to get there in time. That might be the closest to what you are asking for in recent times. (Both President Bush and President Obama were flown to their homes by the Presidential Airlift Group after they left office, and the callsigns were Executive One in both cases, but they were actually using one of the HMX-1 helicopters, not a commercial flight.)

@JScarry, saying the military doesn't have to follow FARs is a very loose and misleading statement.  I am not going to debate details here, but we follow the same rules as everyone else when operating in the National Airspace System.

General aviation (GA) is one of several classes of aviation activity, military and commercial being the two other main ones.
The airliner is a class of aircraft designed to carry a significant payload of passengers and perhaps also freight.
Most airliners are used for commercial operation, both scheduled and charter, but not all are.

I might be a little late here but I don't remember calling the Twin Otter a GA plane. I think I have always considered the Twin Otter an airliner but the word GA plane might have slipped out there. Anyway, for that classification, it doesn't really matter what plane you use but rather what you do with it. The Twin Otter is mostly used as an airliner for example to bring paying passengers to remote islands. If you, a commercial pilot, make money with your flight, and it's scheduled, then it is most likely considered an airliner flight. If you, a ppl pilot, rent a plane and take your family flying, then that's a GA flight - even in a 737.

Thanks for your contribution and welcome to AviationStackExchange. This is a site mainly for factual answers to questions that can be cited with credible references. To comment on another poster’s post, please use the Comment function once you have enough reputation points. While you are right about the differences in GA and airliner being more about the reason it’s being used, it is not as simple as that. Being such, I am unable to find the term “airliner” in the FAR/AIM. And, airline in reference to a company is not in Parts 91, 135, & 136 under which you can fly commercially.

Although I can not find an official FAA definition of airliner, I would classify an airliner as an aircraft above a certain weight and/or seating capacity used in the service of a scheduled carrier. Others may differ on the definition. But, I have paid lift fees to fly in many Twin Otters for skydiving. None of which I would classify as an airliner.


text:
Why does Boeing use a trim wheel in the 737 and not their other products?
Why does Boeing use a trim wheel in the 737 and not any other products?
Is the trimmed state for the 737 just more important than in the 777? Or even 747?
It gives the impression that a secondary control for the trim (If the power to the pitch trim motors have been cutout) is extremely vital, seeing it features two fold out handles that are located 90 degrees apart, so a pilot has good leverage at any point in the rotation to their desired trimmed state.
I take it that this style of a trim system is implemented in the 737 for a good reason, so I’m curious what makes this “style” the perfect fit.
On the 747, and 777 it almost seems that once power to the pitch trim motors have been cut-out, there isn’t a way to manually move the stabilizer? I’m very aware that I could also be 100% wrong, but why not have a trim wheel in all products? Or vice versa?

The B707 and B727 also had trim wheels, so the question should be "later products" rather than "other products".

The B747-100/200/300 had trim wheels too, though it appears to have been removed for the -400 and later.

Trim pitch "wheels" as you describe date back to the time when turning that wheel actually pulled on steel cables that were connected to the hinge mechanism for the control surface itself. This mechanical/manual system was a simple and robust method of manually trimming the aircraft and was very widely used before electronic/fly-by-wire control systems were invented.
Since the 737 is the oldest basic design platform in the Boeing product line, its original design dates back to a time when trim wheels were mechanical and pilots were transitioning out of still older planes into Boeing's new offerings- and those pilots expected manual trim wheels.
It is likely that trim wheels in newer planes are a "legacy" feature, allowing pilots familiar with an older revision of the cockpit layout to transition to another newer plane in the design series.

Keeping the "legacy" flight systems and characteristics is very important to Boeing since it means that pilots need little to no additional training to fly a newer version of an older aircraft. It's what led them into the whole MCAS debacle with the 737-MAX series. +1 from me.

@FreeMan but the problem lies within the decision to use the same flight system, that looks at one sensor at a time, which is the side the flying pilot is on. Had they opened up the computer to read both at the same time, we would be talking about how successful the Max is currently. But it’s not like the failure would be nonexistent. And it’s not like the failure would appear to be something abnormal, or something that a crew hasn’t seen. A 5 decade old procedure was abandoned by the airlines.

@Firefighter1 that's a whole different discussion that's been well beaten to death here and elsewhere on the web - not worth pursuing in comments to an unrelated question. I simply used it as an example of their desire to keep functionality the same in the "same" named aircraft. As you note, other Boeing models do not use the trim wheel because there is no (or not nearly as much) type crossover between the 737 and any others, so one expects to learn totally different systems.

@FreeMan yes it is important to Boeing, but not for that reason. The real reason is that having got a nice deal from the FAA about "grandfather rights", they can keep churning out new versions of old aircraft designs without having to re-certify them to current standards. Well, that was a good business strategy until the 737-MAX problems came along … :)

@alephzero it doesn’t need to be re certified. Boeing does whatever the airlines want, not what Boeing wants to do. Same goes for every manufacturer. In the same sense of your argument, it was a business strategy for the airlines to avoid training. Now that the focus is on Boeing and only Boeing, airlines get to funnel more money to investors that was originally meant for training. Boeing contributed to less than 5% of JT610. And its looking the same for ET302.

The 737 pitch wheels ARE mechanical. There is an electric motor to spin them with a push of a button on the yoke, and turning them by hand gets really difficult when the aircraft is far out of trim, but they are still mechanical. The larger designs have the electric motor inside the tail directly turning a jackscrew and no mechanical link to cockpit.

@JanHudec That is what I have read as well. One of the supposed problems with the recently crashed 737s was that starting with the 737 NG the trim wheels are smaller to make space for a new, larger flight management computer. Because of the smaller diameter the pilots could not exert enough torque/power when they tried to manually move the horizontal stabilizer, severely out of trim  at high speeds.

@Peter, it's not like it would have been much better even on classic; the force increases with speed and how much they are out of trim and they were very fast and very far out of trim.

While the other answers are correct they are missing a key point:
Because it was certified that way
When an aircraft is certified with particular equipment, changing that can be difficult and may require the filing of a MAJOR REPAIR AND ALTERATION form. Its likely cheaper for Boeing to keep the trim wheels the way they are. The common 737 type certificate notes that the airframe was certified against (and must be rigged in accordance with) a particular set of Boeing drawing.

To insure proper operation of the airplane, the movements of the
  various control surfaces must be carefully controlled by proper
  rigging of the flight control systems. The airplanes must,  therefore,
  be rigged according to the following FAA Approved data:Boeing Drawings
  No.
...
65-45104 Control Installation, Stabilizer Trim

I cant seem to find a copy of that drawing but it likely indicates the trim wheel as part of the system.

His question is really at the conceptual level.  As in, why not do that on newer designs.

The leading edge of the horizontal stab on jets is driven up and down for trim using a very large acme thread style screw jack.  The Cessna 180/185 family and the Piper Cub/Super Cub/Pawnee family also do nearly the exact same thing, just with much smaller cable operated screw jacks.  The early jets using jackscrew driven stabs included electric motors but maintained the manual cable-drum drive out of design conservatism, up through the 737.
The cable system is a lot of weight and maintenance, and the loads on the jack can be high enough in some out-of-trim flight conditions where you can't actually move the surface manually until you temporarily unload the stab with a large elevator input.  In the case of the Ethiopian crash, they were boxed in by this problem by being too fast and too close to the ground - the elevator control inputs required to unload the screw jack so they could turn it would have made them dive even steeper (Piper Cubs also suffer from this problem where the little cable drum slips and you have to unload the surface to get it to move - on the 737 you just can't move it with the little wheel).
Then when you get to ever larger aircraft, to have a manually operated screw jack would require a cockpit wheel the size of a ship's helm, so in the late 60s and 70s, the designers developed multi-channel electrical control with sufficient redundancy to meet the single-point-of-failure risk standards without a mechanical system (they weren't "fly-by-wire" actually, more like "control-by-wire"; in CBW, the output is the same as the input but it's just done electronically, in FBW, the output is what a computer decides it should be after receiving the input command and may vary significantly from the actual input).
Anyway, bottom line is multi-channel control by wire stab systems (and FBW systems on FBW aircraft) meet the risk requirements to deal with trim failures (quits working, or runs away). The risk requirement for stab failures is not that high, usually categorized as "Major" in the Minor/Major/Hazardous/Catastrophic risk hierarchy, which determines minimum redundancy levels in design, and a dual channel CBW system with the appropriate controls and indicators meets that without old style cables (Boeing used that logic to justify the MCAS's sketchy architecture in the risk analysis - that's really where the ball was dropped).

Ethiopian was like 7000' AGL. I keep hearing this meme that they were close to the ground, but go look at the data.

The problem with the Ethiopian flight was the high speed, not so much the altitude. They were flying with the clickers (overspeed alert) active, so the aerodynamic forces on the vertical stabilizer were much larger than usual.

@Harper, 7,000' is not that much if when you need to do a push over for significant time. Of course you can do a pull up first, but they were struggling just to keep it level.

It's the high speed + the altitude.  Push over at 300 kt+ in a jet and the ground 7000 ft below you looks like it's only1000.  In a jet, time and space are compressed.  In a C-172, you operate in a mental perceptual box maybe 5 miles across and a coupe thousand feet deep.  In a jet that same mental space is 25 miles and 10000 ft.  It's what is meant by "staying ahead" of the aircraft.


text:
How does an Airbus aircraft connect to the Internet?
I would like to understand better where (physically in the aircraft) and how the Internet connection is received on an Airbus aircraft, in particular in an Airbus A380, and then how this system is linked to the access points that serve the passengers. What path(s) bring(s) the connection from the antenna to the access points that make it available to the passengers?

Related: How does WiFi work on an aircraft?

@mins Not just "related"; it's an exact duplicate. At least, there's no reason to assume that Airbus is any different from any other manufacturer in this regard.

@DavidRicherby: Well, you're right, for many users WiFi, Web and Internet are equivalent.

@mins If the question cares about the difference between those three things, it's a question about computer networks, not about aviation. Otherwise, both questions are just "How does wireless internet work on commercial passenger planes?"

There are three different ways that aircraft can give internet access to its passengers, which will most likely be on at around 38,000 feet. First off, to have Inflight wifi, there needs to be a ground-based internet server, a transmitting dish, or a satellite dish. There must also be a receiving and transmitting antenna on the aircraft and an onboard server and a Wi-Fi router.
The first system is the ATG system, which stands for Air-To-Ground transmission. It requires two antennas that are installed on the belly of an aircraft so that it can pick up signals from the ground-based cell towers. With this system, a passenger can receive at least 3 Mbps and one of the highest currently is 9.8 Mbps by gogo wifi.

The next system is the "Ku-Band" Service, which was formerly used by the military. K, short for Kurz (meaning short in German) and u for under the original NATO/K-band frequency range. This system works by a ground station sending signals to a satellite first, and then reflect off the satellite and send the signals to the aircraft. The signal is then decoded and then transferred to the router. This can deliver about 50 Mbps with this system, but you still have to consider that there will be more than a hundred passengers on the aircraft. Since this system has to send signals to a satellite first, there could also be delays on signals and could get slower as more aircrafts use this service. If you've seen aircraft with a pod on the top of its fuselage, you may not know that under it sits a satellite antenna, which rotates and can adjust itself to the nearest satellite.
The last system is the "Ka-Band" Service. K still stands for Kurz, and a stands for above since this is in the upper region of the native frequency band which is at 20–36 GHz. This service can deliver about 70 Mbps. Presently, there are two ViaSat (a satellite wireless service provider) Ka-Band satellites, one covering the US, and one covering Canada and parts of Europe.
Some aircraft even have a hybrid system, so they can use Ku-Band and Ka-Band service depending on which has a better signal at the time, so it would depend on the internet speed on which the A380 you are referring to is.
An onboard server will be required on the aircraft for an Inflight Entertainment system, which will run three services: a media server, a DRM (Digital Rights Management) license server, and a device provisioning server. The media server is for storing your content keys (but doesn't necessarily have to be on the media server, it can be on a separate onboard server). The device provisioning server will need to store a reserve of device personalities (unique device credentials) for distribution to onboard mobile devices (via your mobile app) upon request. The signals from the satellite (in a Ku/Ka-Band service) will be transmitted into the pod/antenna, then into the onboard server, which will be transmitted to several routers distributed throughout the aircraft. For example, an A320 or a B737 usually have two routers. The signal is sent to your phone, then signals will be sent back to the antenna, then to the satellite, which is passed back to the ground.
More about in-flight wifi at HOW does WIFI WORK on AIRPLANES? Explained by CAPTAIN JOE

Comments are not for extended discussion; this conversation has been moved to chat.


text:
Why does Martin-Baker use a Gloster Meteor as a testbed for ejection seats?
Martin-Baker uses a Gloster Meteor for testing ejection seats, according to their website.
While it's a stylish plane, and a true delight that there are still airworthy fuselages of this plane left, it seems strange to use such an old aircraft as a testbed.

The Gloster Meteor was one of the very first turbine engine planes, made during the Second World War. In terms of electronics and structure it's a far cry from a modern fighter.
How does this make sense? Wouldn't it be better to test ejection seats in the aircraft they will be used in, with the correct structure and canopy?

So, how would you recover the test-plane after the test of the ejection seat?

@DJohnM The pilot doesn't eject. In the photo you can see the pilot under the canopy at the front and behind him is an open section with the ejector seat in it. They only eject the seat and a very high tech "crash test dummy" so the pilot just flies the aircraft home again.

I would much, much rather test an ejection seat in a two-seater plane than in a single-seater. Just because :)

Just as an info for those who wonder why they don't eject real people when they test ejection seats: ejection is brutal. About 30% of them will receive permanent injuries, and there is about 10% chance of not surviving it at all. And that's with ejection seats in active service. With experimental and untested ones it might be even worse.

@RobertColumbia flying home in an aircraft that's missing a sizable part of the cockpit canopy doesn't sound like a whole heap of fun either though!

@scotty3785 My comment was directed at the OP's question about using the intended plane to test the ejection seat.

@stripybadger - frankly, it looks like the entire flight is made without the canopy over the rear seat. It very much looks like there's a seat in the second position in that picture meaning the ejection test hasn't yet happened.

@vsz they used to use real people to test the seats, but have since moved to using crash test dummies instead.

Aviation week did a bit on the plane last year

"In spite of its considerable vintage, the sturdy British attack
  aircraft has all the attributes required for a stable, high-speed test
  platform" says Andy Gent, Martin-Baker’s head of flying and chief
  pilot. “From a test perspective the Meteor is ideal. The tail boom is
  fairly long and the fin is not very high. The engines are also spaced
  out a fair way out along the wing, so the efflux from the ejection
  test and exhaust from the gun and rocket motor isn’t potentially going
  down the engine intakes,” he says.
Based at Martin-Baker’s Chalgrove, England, test facility, the fleet
  is made up of two Meteors, WA638 and WL419, both of which have been
  with the company since the 1960s. “They are doing the job so why would
  you ever go through the heartache of getting another aircraft?” says
  Gent.

In short, it does not fly all too much, it gets the job done and its well built. Similar reason most older aircraft are still flying these days.
The article goes on to say that they have little intention of changing this any time soon:

Marketing Director Andrew Martin notes the company is one of only a
  handful that performs airborne ejection tests, and that the Meteor
  will continue to be used for the foreseeable future. “It is a tough
  thing to evaluate, and right now while we have these phenomenal assets
  we are not going to really think about a replacement in great detail,”
  he says. With the final retirement of the last Royal Air Force
  (RAF)-operated aircraft in the target towing role in the early 1980s,
  Martin-Baker acquired a large stock of spares and Rolls-Royce Derwent
  8 turbojets. Because of that and the ample remaining airframe life,
  the company is no rush to find a successor.

Also a bit of a side note, this is not their only testbed. MB also uses a high speed sled for testing at their Langford Lodge, Ireland facility. This allows ground testing of the seats at flight speeds. They also test static scenarios in what appears to be cockpit mock ups as generally speaking seats are certified for Zero-Zero use. Varying governing bodies may require different testing and live demonstrations as per their certification process leading to different testing procedures.

Ok, so the canopy and air-frame test is basically performed on the ground, while the Glosters only serve to test high speed performance?

@vidarlo the sled allows high speed testing on the ground as well. Im not sure exactly what cases require in air testing. I would think it depends on which governing body you are certifying for and what their requirements are.

could you add a bit about that in your answer, and I will accept it :)

@vidarlo Ive added some more info to cover

@Dave my guess is the flying test is among others to test ejection sequences at high altitude. Lower air pressure, different behaviour. And the sled track of course is rather too large to put in a pressure chamber.

Also the sled can't be used for unusual attitude tests—the seats need to be tested also in bank and inverted flight as they are supposed to right themselves before opening the parachute.

Do they actually test by ejecting the real pilot? Or a crash dummy?

One other factor to consider... Aircraft designed in the pre-computer era tended to be overbuilt, as they didn't have the computational power to calculate stress loads to the level of detail that can be achieved today.
Since ejection does put some unusual stress on the airframe, not normally a concern as ejection is almost always followed by a crash, it makes sense to use an older, stronger airframe that is less likely to suffer from the stress of multiple ejections.
How many DC3's are still flying?
It is neat to see Meteors still being used. A handsome aircraft.

Another advantage on using the same aircraft is that the aerodynamics are constant so you eliminate one variable in the test.
Eg when testing a new model, you can compare its performance with the test of the previous model in the same airframe and you don't have to worry about any differences in the the airflow around the fuselage and cockpit as they are the same. Also the seat will fall through the wake of the aircraft and this can vary greatly from aircraft to aircraft.

That doesn't seem particularly relevant. The differences between planes may well be big, but they're small enough that a test on a Gloster Meteor is good evidence that the seat will work on whatever aircraft it's installed in, which certainly won't be another Meteor. If they got a new test plane, they could always re-run some tests to compare the same model of seat betwen those two planes.


text:
Why don't we see business jets with wingtip fuel tanks anymore?
There is something I miss from the Learjet 35 (one from FS95/98) that I don't see any more:
Fuel tanks on the wingtips!
What happened to the wingtip integrated fuel tanks in the business jet industry?

One of the main reasons wing tip tanks were used was to counteract some of the forces of wing bending by adding mass to the end of the wings. As time has progressed and our understanding of materials has grown as well as our ability to design structures better the need for tricks like this has gone away.
As our general understanding of aerodynamics has gotten better so has the understanding of the impact of wing tip shape on reducing drag. As such wing tip tanks have been traded out for wing tip devices.
In some cases the tip tanks are an option available as a later add-on or at purchase time. Generally this increases the range of the aircraft at the cost of useful load. As such, it may just be that most people who order planes these days prefer the higher useful load and the reduced range, rather than the extended range flying with a lighter load.
You can find some more discussion on it here.

More modern engines need less fuel for the same thrust, so the fuel volume needed for an acceptable range has shrunk over the last five decades. Wing volume alone is now more than sufficient.
While a typical 1950s era jet engine would consume 1 pound of fuel for every hour and pound of thrust (= 28 g/kN·s), comparable engines of recent design consume less than half of that (0.44 lb/lb-f·h in case of the PW500).
Note that even entry-level business jets have a range in excess of 2000 km, without tip tanks. The use of supercritical airfoils, which allow thicker wings for the same drag divergence Mach number, helped as well to make tip tanks superfluous.

NB: For the second measure 0.44 lb/(lb-f*h) is equal to 12.5 g/(kN*s).

The Lears with tip tanks were the 23-25 and the 35. They had laminar profiles with 9% wing thickness, the thin profile was to not have to apply wing sweep. The Lear 23 was developed from a Swiss fighter design, Bill Lear Sr. sold his electronics company, bought the design, and founded his bizjet corp. Hail Bill!
Story of Bill
Internal fuel volume of a thin wing is a limiting factor. Storing fuel at the wing tip is a very good idea that is still carried out in all aircraft: internal fuel at the tip is used last as well. The external fuel tank further doubled as an aerodynamic barrier device, like a winglet.
However, tip tanks increase drag and therefore if at all possible to provide the range, will be stored inside the wing.

You said "external fuel tank further doubled as a barrier device", but wouldn't a collision with a fuel tank be worse than just hitting a regular wingtip?

@Xen2050 barrier device as in aerodynamic barrier, like a winglet. The tip tank blocks off the wing tip and reduces induced drag a bit, however the profile drag is greater than the induced drag reduction and the L/D is lower.

Ok, that makes sense :) I tried searching before asking, but only found hits related to double-walled fuel tanks & impacts.

Anonymous downvoter, how may I improve my answer?


text:
Could this "Wingless Dodo" fly in real life?
There is a wingless Cessna in GTA 3 that is so impossible to fly that the game counts how many seconds you manage to fly it.
Would that plane fly at least 1 second in real life?
The plane looks like a C152.
Here's a video where that plane appears.

Yeeaaahhh.... No.

"impossible to fly" - there is no such thing as "impossible" in video games.

RFC 1925 comes to mind: "With sufficient thrust, pigs fly just fine. However, this is not necessarily a good idea. It is hard to be sure where they are going to land, and it could be dangerous sitting under them as they fly overhead."

The minimum speed of a Cessna 152 is 43 knots while the maximum speed is 110 knots. If the wing area is reduced to one half of its original size, and we accelerate to twice the minimum speed, the induced drag is half as much as that of the original airplane at minimum speed (but still eight times higher than that of the original airplane at the same speed!).

Dynamic pressure scales with the square of airspeed, so it grows by a factor of four.
Lift coefficient and aspect ratio are half as much as before,
so the induced drag (which scales with lift coefficient squared over aspect ratio) is only half as much.

Now to friction drag: If the surface area would remain unchanged, the doubling of speed quadruples the friction drag. Since friction drag is dominant at high speed and the original engine and propeller managed to overcome that drag at 110 knots, it would at most be 61% of that drag at 86 knots. Engine power is constant over speed and thrust proportional to the inverse of speed, so the excess thrust at 86 knots would be 28% higher than at maximum speed, leaving an excess thrust for induced drag and acceleration of at least 67%, which should easily be sufficient for takeoff (if the runway is long enough).
I would only be worried about the lack of ailerons - they have been cut off with the outer wing as well.
Theoretically, the clipped version should be capable of a higher maximum speed, but that would most likely be limited by tail flutter and dropping propeller efficiency.
While clipping half the wing will still render the result somewhat flyable, if more than half of the wing is clipped, I would start to doubt that it can be brought into the air without further modifications.
When the Luftwaffe tried to train pilots for the Me-163, they turned to gliders with clipped wings, so their minimum speed would more closely resemble that of the rocket-powered interceptor. The DFS Habicht (hawk) aerobatic glider became the Stummelhabicht (stumpy hawk) when new wings of reduced span (from 13.6 m to 8 and later only 6 m) were fitted.

Stummelhabicht (picture source). It was fun to fly, but all speeds were quite a bit higher than those of the original glider. After all, it was built to prepare pilots for a glider with a landing speed of 200 km/h.

There is an old saying "If you put a big enough engine on it, you can make anything fly."
The Lockheed Starfighter was a classic example of that. With its short stubby wings it is basically a guided jet engine / missile.

With small wings you have two issues. Obviously, the sheer lack of lift at low speeds, but also the lack of control surface area at those speeds. If you go fast enough it balances out, but takeoff and landing become a major challenge.
Could you do that with a modified stock Cessna?
No. The airframe simply would not be strong enough to support the required engine and the drag would be horrendous. At the airspeeds you would need, it would break up.
Could you build something that looks like a stock Cessna but with stubby wings? With enough money and resources, I'd guess anything is possible. Either built like a truck with a huge engine, or some ultra-lightweight version. But it would be a novelty, an airshow item at best.
Speaking of making anything fly... these are always fun to watch...

One of the things that actually helps the (tractor) prop-driven versions over the jet is the propwash over the control surfaces, which (especially now that reprogrammable IMU-based flight stabilization computers show up in $13 toys) means you can hover by hanging on the prop.

In the same vein I have seen some flying witches on brooms. Prop/engine in the handle-end of the broom and the witches cape acted as wing. Most of the which doll was made out of Styrofoam and the broom from balsa to keep it as light as possible. Big success flying them over the crowd at an Halloween festival. Google "flying witch model plane" for samples.

This depends on if you modify the wing or not. If you are asking the question:

If you chop 3/4 of each wing off will a plane still fly?

The answer is more or less no. The wings simply won’t generate enough lift which is a factor of their size and shape.
It may actually be possible that at a very high speed the nub wings would generate enough lift to fly but your body design may be the limiting factor there.
If you are asking the question:

Can an airframe be modified to fly with stubby wings?

Then the answer is yes. On the extreme side you really don't need wings at all if the body is designed to generate lift. Although never really commercially a success NASA experimented with lifting bodies for a while.
There have been flight capable aircraft with some pretty small wings and generally a wing can be made shorter by increasing its camber but there are practical limits to this from a drag sense.

There was the RANS S-11 experimental.  Apparently intended as a kit-built, though I don't think it was ever sold: https://www.eaa.org/en/eaa/aviation-communities-and-interests/homebuilt-aircraft-and-homebuilt-aircraft-kits/kits-and-plans/r---s/s-11-pursuit


text:
How might one obtain aircraft registration numbers for past flights (months ago)?
I am trying to obtain tail numbers for some flights to retrospectively complete my 5 month old's new passenger flight log book. Antonakis, FlightRadar24 and FlightAware sites are not giving me the answers since the flights took place too long ago.
This is the flight information that I have:
Flight No.    Date          Route

AC 8036       29/10/2015    YYZ-PIT
AC 8037       02/11/2015    PIT-YYZ
AC 7508       05/12/2015    YTZ-YUL
AC 7521       12/12/2015    YUL-YTZ

Any help or instructions on where to obtain info would be greatly appreciated.

Note that this question is not a duplicate. This question is not answered by the question, How to determine the aircraft tail number on a particular flight?, since these flights occured too long ago to be found through the methods discussed in the answers to that question.

Try checking the airline's site, they may or may not not be there though.

Try this site

@TomMcW It looks like he already checked there.

@SMSvonderTann Ah. I missed that.

In theory for flights in the US(and possibly to/from the US), you can look for data through the DoT's Bureau of Transportation Statistics. The data is reported there, but I'm not positive on how to find it through all the data available there.  http://www.transtats.bts.gov/Data_Elements.aspx?Data=2

For some flight, you can find the info using the "Historical Flight Status" on www.flightstats.com (check the event timeline for "TAIL Changed"), however this is not true for all flights (seems to be airline-dependent).

A note, those flights were likely not operated by Air Canada, but probably another airline. The high flight numbers are a good sign of that. If you can figure out the airline, it could help you quite a bit.

In fact, AC8036 was a flight operated by Jazz Aviation. The aircraft seems to be a Bombardier CRJ. That should help you narrow down things, would it not? (Of course, this is for the latest flight that happened)

If you come up blank on the various open sources that have been suggested, which wouldn't surprise me, your best bet may be a personal letter to Air Canada and another as well to whatever headquarters address you can find for Jazz, explaining what you are attempting to do, and asking if they'd be willing to look up the aircraft ID for those flights for you.
For the right person, it's probably about 2 minutes of work total to look them up, although getting the request TO that person may take considerably longer.  Many airlines have customer relations departments whose job it is to address whatever issues people write in about, and a pleasant "we flew with you, flight was great, love you guys, silly us, forgot to get the tail #, baby's logbook, dedicated customers, please help, really love you guys, thanks millions..." letter may well get pointed to the right department and get you an answer.
You could also try calling and/or e-mailing; you're actually NOT looking for the standard front-line Reservations agent or "let me help you with your flight" type of person, but rather somebody in the Dispatch or Maintenance records section, as those are the people who have the big database of everything that the airline has ever done.  That said, it may be difficult to get past the usual barriers that airlines have in place to keep worried passengers in an airport from trying to talk to dispatchers about "why isn't my flight here yet???"  So I'd expect that the pleasant letter to a Customer Relations department may be your best bet.

Cheers Ralph. Appreciate the suggestion, sound advice!